In machines of this kind the pressure, with which the material from the inlet hopper is fed to the cutting device, depends on certain parameters of the machine and the material, said parameters mainly being of a "static" and not a "dynamic" nature, since they relate to the shape of the conveyor worm and the material's ability to withstand internal shear, as well as its viscosity, if any. It is not possible to increase this feed pressure by increasing the speed of rotation of the conveyor worm, as this will--when a certain speed limit is exceeded--cause the worm to loose its grip on the material and rotate freely in it.